MalacostracaMal`a*cos"tra*ca\, n. pl. [NL., from Gr. ? soft + ? shell of a testacean.] (Zo["o]l.) A subclass of Crustacea, including Arthrostraca and Thoracostraca, or all those higher than the Entomostraca.
|largest subclass of Crustacea including most of the well-known marine, freshwater, and terrestrial crustaceans: crabs; lobsters; shrimps; sow bugs; beach flies|